Adds lock for create from vol/snap to avoid race conditions

This patch protects create from volume/snapshot by using a
lockfile to protect the operation from concurrent deletes of
the volume/snapshot used in the create operation.

Currently, if a volume/snapshot is deleted while a volume is
being created from it that delete may complete during the
create operation thus leaving the new volume in error or stuck
state. This lock will ensure that:

(a) if a create of VolA from snap/volB is in progress, any
    delete requests for snap/volB will wait until the create
    is complete.

(b) if a delete of snap/volA is in progress, any create from
    snap/volA will wait until snap/volA delete is complete.

Co-authored-by: Takashi Natsume <natsume.takashi@lab.ntt.co.jp>
Closes-Bug: 1251334
Change-Id: Ie4bc0af789ab232593f55aa2f6b34345eb9b9929
Brick LVM: Set C locale when gathering PV info

Some locales use commas as decimal separators, which means
that code breaks when someone expects to be able to use the
PV size as a float.

Change-Id: Idceb405e021ea8a0f44e19be43bad1307fbbb51c
Related-Bug: 1219963
Returns thin pool free space calculated from actual usage

This change adds a hidden method which calculates the thin
pool free space from the data_percent LVM options and reports it
accordingly in _update_volume_stats()

Change-Id: Id6a69644505ca10811db458ea90ed10f643054b2
Closes-Bug: 1249782
Sync rpc fix from oslo-incubator

Sync the following fixes from oslo-incubator:

ef406a2 Create a shared queue for QPID topic consumers
e227c0e Properly reconnect subscribing clients when QPID broker restarts

Change-Id: I934a6ea6e9eb510513640870750ea37e6f076df9
Closes-bug: #1251757
Closes-bug: #1257293
Merge "Returns thin pool free space calculated from actual usage"
Merge "Sync rpc fix from oslo-incubator"
Merge "Adds lock for create from vol/snap to avoid race conditions"
Merge "Brick LVM: Set C locale when gathering PV info"